Catalyst activator for diolefin polymerization



Patented Mar. 10, 1953 UNITED STATES PATENT OFFICE QATALYS-T ACTIVATOR .FOR DIOLEFIN POLYMERIZAT-ION No Drawing. Application June 15, 1949, Serial No. 99,346

22 Claims. (01. 260-825) This invention relates generally to the catalysing of free radical initiated polymerization systems by metal-organic complexes. More particularly it relates to catalyst activation of peroxy induced free radical polymerization systems by soluble sequestered ions of heavy metals in combination with organic chelate-complex forming reagents.

' In the customary method of polymerizing conjugated dienes such as butadiene, isoprene, dimethylbutadiene, chloroprene, methylpentadiene, and others, with or without vinyl compounds such as styrene, acrylonitrile, methylmethacrylate or similar compounds the monomers are reacted in aqueous emulsion in the presence of emulsifiers, catalysts, modifiers or regulators, activators, promoters and other suitable additives. In the temperature range 86 F. to 150 F. the reaction proceeds at rates which are practical for commercial production when such well known initiators as potassiu n persuliate, hydrogen peroxide and other peroxy compounds are used. It is the general feeling in the art, however, that superior polymerization products are to be obtained by carrying out the reaction at much lower temperatures. At these lower temperatures the effectiveness of the generally accepted catalysts or initiators such as persulfates, hydrogen peroxide, and organic hydroperoxides or diperoxides is markedly reduced so that the reaction time to a practical degree hydrocarbon conversion may be many days or weeks. The use of certain heavy metal inorganic complexes has been found to restore the effectiveness of the catalysts or initiators to the point where the rate of reaction at the lower temperatures is comparable with that experiencedat higher temperatures without the use of such complexes.

Ferrous pyrophosphate has been favoured among the known activators and in some respects is satisfactory. The preparation and application, however, is often quite critical. For optimal results it may be necessary to dissolve separately one or both or" the components usedin its prepa ration and to add one to the other in a particular manner and at a definite rate. A suspension of the relatively insoluble pyrophosphate varying from a thick paste to a faintly milky solution is thus achieved. A rapid deterioration of this suspension, when in contact with air, may be expected particularly if optimal results can be achieved only by aging or conditioning the suspension at elevated temperatures for even a brief interval of time. Also the suspension seems to change its activity with time due to possible physical changesthereby requiring close supervision of the reaction and adjustments in the amount of pyrophosphate activator used. Being a suspension or a sludge'constant agitation is necessary if the metallic ion concentration is to be uniform throughout. For the same reason it is more difiicult to transfer, to meter accurately, and hence to control the rate and 'quan tity' of addition. Of the ferrous ions introduced into the system .a certain proportion may become incorporated into the polymerization product i in spite -or" the best washing techniques. This is considered "to be a further disadvantage as the presence of certain metals is thought to increase the heat softening tendencies of the rubber in the driers and to reduce the age resisting qualities of the rubber produced.

The preparation and application of such additives to low temperature peroxide initiated free radical polymerization systems is illustrated by the following generally accepted recipes:

RECIPE A Parts by weight Butadiene 71 Styrene 29 Tertiary mercaptan 0.2 Trisodium phosphate decahydrate 0.5 Emulsifier-sodium salt of a dispropor- 5.0

tionated rosin acid. Sodium hydroxide 0.05 V/atertota1 180.00 Cumene hydroperoxide 0.15 Glucose 1.98 Sodium pyrophosphate 0.36 Ferrous sulfate heptahyd-rate 0.10

RECIPE B Parts by weight Butadiene 71 Styrene 29 Tertiary mercaptan 0.24 Potassium chloride 0:5 Emulsifier-potassium salt of a dispropor- 4.7

tionated rosin acid. Disper-sing agent 1 Q 0.1 Potassium hydroxide 0.13 Water 180.00 Cumene hydroperosidauucfi i0l10 Dextrose 100% 10 Potassium pyrophosphate 0.177 Ferrous sulfate heptahydrate 0.14

Believed to be a naphthalene sulfonate-formaldehyde polymer.

The last three components, the sugar, the .pyrophosphate and the ferrous "sulfateare normally added. to the. chargeasan activator.

In the normal practice of Recipe A to 10 parts of water add the pyrophosphate, the sugar and the ferrous sulfate. This is brought to a boil for 5-10 minutes to digest the sugar. The suspension or sludge formed is brought up to weight by adding boiled water. In the practice of Recipe B the sugar is digested in 40 parts of 0.1 KOH until the pH has decreased below i. e. by boiling for approximately ten minutes. The activator is prepared by dissolving the ferrous sulfate decahydrate and the potassium pyrophosphate separately, each in 5 parts of Water at 140 F. The two solutions are then mixed by pouring slowly with stirring and under a blanket of nitrogen the ferrous sulfate solution into the solution of pyrophosphate. The mixture is then maintained at 140 F. for -30 minutes, preferably in the absence of oxygen. The sugar digestion solution is usually charged separately from the activator which may be added before but preferably after the hydrocarbons and before or after the catalyst. The less satisfactorly results to be expected when this critical routine is varied will be fully demonstrated below.

It is the object of this invention to effectively increase the rate of reaction in such peroxideinitiated free-radical polymerization systems at such reduced temperatures through the introduction of an additive which does not embody any of the disadvantages enumerated above and which is easily prepared in some cases without heating, is completely soluble, and is stable.

It has been found that through the use of organic chelate complexes of certain heavy metals derived particularly from compounds containing the group the reaction may be adjusted to a desirable rate. of particular value are certain of the compounds derived from ammonia, amines or polyamines N-substituted with two or more carboxyl, alkyl carboxyl, or aryl carboxyl groups. In addition to the apparent advantages of a very soluble and very stable activator an additional and unexpected advantage resulting from the practice of this invention is that appreciably smaller quan tities of the heavy metal are efiective. These soluble heavy metal complexes may be selected from a wide range of metals and also by the wide variety of organic complexes which fall within the above definition. However, as hereinafter indicated not all metals are immediately useful since it is well known in the art that the polymerization recipes must be critically adjusted for optimal results. Also of the many organic complexes as above defined only two are believed to be available commercially. Our best results have been achieved with ethylene dinitrilo tetra acetic acid nooo-oH, H H CHz-COOH lanai t t nooo- Hi E H Hr-COOH I or more accurately since the reaction will be conducted in an alkaline medium, its Na, K or NH& salts. Other salts of this polyacid would be satisfactory providing the metal ion is replaceable by the heavy metal ion which it is desired to sequester. Na and K salts are particularly advantageous although potassium salts are often preferred since higher polymerization rates may be observed when they are used. Ammonium salts are less acceptable as ammonia or its salts are not considered desirable in the polymerization mixture.

Reacting the soluble salt of the heavy metal selected with the organic complexes indicated we find that a soluble complex is formed which ionizes only to a very small degree. Using ferrous sulfate and the sodium salt of ethylene dinitrilo tetra acetic acid a complex is thought to result which according to the literature has the follow- Similarly, if a sodium (or other soluble) salt of nitrilo triacetic acid is employed with ferrous sulfate the following complex results:

NaOOC-CH:

N Fe N g NaOOC-C 2 CHr-COONB.

Another group of compounds are those in which the ammonia, amine or polyamine is substituted by aryl carboxylic groups, e. g. salicylic acid. In the practice of our invention this type of complex has not been found suitable but we believe that this material and its analogues can be used by proper adjusting of our experimental condiions.

Another group of compounds which we have found suitable are those in which the H2 CHFGOONa Example 1 Compounding the additive normally is accomplished in the following manner:

To 10 parts of water add: 0.82 part of a 34% ((NaOOCCH2) z--NCH2)2 soln., 1.68 parts of 78% confectioners glucose, 0.03 parts FeSO4J7I-l2O, bring to a boil and boil for 5-10 minutes to digest the sugar. The resultant solution is uniform, clear and stable. Bring the solution up to weight with boiled water and add in the usual manner (just prior to the catalyst) to a variation of Recipe A, namely:

- Parts Butadiene 7 1 Styrene 29 Water (total) Emulsifier 5 Na3PO4.10I-I2O 0.5 Cumene hydroperoxide 0.24 Mixed tertiary mercaptan 0.2 NaOI-I 0.025

66% conversion may be expeotedrafter 17 hours reaction at 41- F. Note that the FeSO4.7I-I2O has been reduced to 0.03 parts and-that the solution is stable and uniform requiring no agitation.

6 When treated and used as in ExampleZ, 28% conversion of hydrocarbons resulted after .17 hours at 41 F. Though much lower than previous results the rate of reaction is nevertheless considered practical.

, 6 Examp e 2 x mpl 5 1.0 parts water The applicability of this activator to butadi'ene- 0.45 part of 34% ((NaOOC-CHzlz-N-Clhh acrylonitrile copolymerizations is illustrated b y 50111- 10 the preparation of a latex by thefollowingrecipe 0.30 part .NasPQlOI-IzO at 41 F: 0.90 part 100% dextrose Parts 0.03 part FeSO4.7H2O Butadiene i511 Acrylonitrile 7 50 when treated as in Example 1 and added to the Cumene hydropemxide 0,1 same recipe from which NaaPO4.10I-I2O is omitted Mixed tertiary mercaptans r 1 66% conversion of hydrocarbons results after sodiumtsalt of disproportionated rosinadds 24.17 reacting for 1'? hours at 41 F. Pot sium hydroxide 0.113 Potassium chloride 050 Example 3 Dextrose 0.10 10 parts water v zfi agent I I 7' 7 @130 0.45 part 34% ((KOOCCH2)2-N--CH2)2 soln. 0.90 part 100% dextrose and an activator composed entirely ofsod umeth- 0.1-4 part FeSOe'II-IzO ylene dinitrilo tetra acetate 0.15 part andwater 10 0.13 part KOH parts. This reacted to 45% solids 100% conversion) in only 16 hrs. "Note that in this e?- ample the chelate forming complex alone wi h xi gz gf gg g 233 1 and added to a the very small amounts of ironinormally present 0 p in the reagents was suffic ientto (bring about an excellent rate of reaction. Parts Following the normal practice of adding the Butadiene 71 digested sugar solution separately, a series of Styrene 29 activators each containing 0.14 part FeSO4.'7I-I 20 Water (total) 180 were made up with various inorganic, organic Emulsifier 4.7 and chelate forming materials indicated except K01 0.5 that with pyrophosphate the preferredpractice Dispersing agent 0.1 was followed of aging at 140 F. for-30 minutes. Mixed tertiary mercaptan 0.24 All others were made up at .room temperature. Cumene hydroperoxide 0.177 The conversion of hydrocarbons to polymer after conversion of hydrocarbons resulted after 40 17 hours at 41 F. in each case is shown in the 1'? hours at 41F. following table:

Compound Parts pH Conv. Description Percent N n .11 solution. pyrophospbate 0.17 9.9 78 ilnesuspension. ((KOOC.CH2)2NCHr-)2 0.45 12 73 precipitate ((NaOOCCH2) -N-OH 0.4 13 09 190. ortho-phenanthroline.-- 0.20 2.7 44 solution. a,a-bipy'ridyl 0.16 3.9 34 130. nitrilo triacetic acid 8: g g? :33: monastral blue 6.2 precipitate disalicyl-ethylene diamine 0.32 12 5 Do. monastral green 4. 3 Do.

0. 33 6 31 solution. 0.34 10 69 Do. 0.42 7.0 34.5 Do. 0. 49 0.4 27.4 Do. 0. 50 9.0 24 Do. 0.41 5.0 22.4 Do. 0. 42 10. 5 18 percipitate. 'K-phthalate 0. 14 5 22 solution. ferrous gluconate 0.225 5.0 11.0 Do. K4Fe(ON)0 no additional Fe 0.21 6 D0. no activator at all 3. 0 .arsenious oxide 0.1 12.4 2.8 precipitate. tannic acid 0.65 3.9 1.0 solution. ferrous phthalocy nin 0. 29 0. 0 Do.

In some cases a precipitate may form, presumably due to ferric iron formation. For protection against oxygen it may be advantageous to add the sugar either alter digesting with alkali or without previous digestion. Such activators are active and completely. or largely free of precipitation. Alternatively, completely soluble activators maybe prepared by adjusting the pH to lower values.

Example In considering the suitability of various heavy metallic salts, activators for use in a variation of Recipe B were prepared with a constant amount, 0.45 part, of ((KOOC-CH2)2-NCH2)2 and 76'the indicated quantities of the various salts.

10 parts water 0.11 part of 34% nitrilo tri-acetic acid soln. 0.45 part dextrose 0.30 part Na3PO4.10H2O 0.03 part FeSO4.7H2O

7 With the reaction conducted at 41 F. the following results were recorded:

Metal Parts pH Oonv. Time Hours ferrous sulfate heptahydrate 0.1140 17 ferrous ammonium sulfate hexahydrate 0.188 ferric sulfate monohydrate 0. 142

aluminium sulfate hexadecylhydrat at all sodium tungstate dihydrate calcium chloride 0. 058 mercuric iodide. 0. 229 arsenious oxide 0. 1 copper sulfate pentahydrate. 0. 126 nickel nitrate hexa hydrate.-. 0.1.46 cadmium chloride 0. 092 mangenous chloride tetra hydrate 0. 0096 cobaltous nitrate hexahydrate. 0.1464 cobaltous chloride hexahydrate.-. 0.109 lead acetate trihydrate 0.191

zinc chloride. cuprous chloride l Precipitatc formed.

Various additives were prepared according to the following pattern for use in a variation of Recipe A (see Example 2) These two tables illustrate the efiect of concentration or recipe on the relative effectiveness of various metals. It follows that where another metal is substituted for iron an improved conversion might be achieved by adjusting the recipes, concentrations, etc.

Whereas in Example 3, 0.14 part of FeSOrJZHzO were used the following table illustrates the efiect of reducing this quantity or even eliminating the salt completely while still maintaining practical rates.

FeSOflH O, parts By comparison it may be pointed out that in a 10 parts water pyrophosphate activator if FeSOrflHzO is re- 0.45 parts 34% active duced from 0.14 to 0.112 conversion is reduced ((NaOOCCH2)2-NCHz)2 soln. from 78% to 60.3%. This lack of sensitivity to Part5 NQBPOMOHZO- amount of iron is an unexpected and desirable 0.45 parts 100% dextrose (50% of quantity in Ex- 3 characteristic of this invention 3 5: dmhantit of metal salt Further unexpected advantages are found in c y 17 h t 41 F d its insensitivity to technical errors, and the varif giig g 25 12:; aig an ations in technique of charging as comparedwith g 40 the critical conditions imposed by a ferrous pyro- Pement phosphate activator. In the following illustra- Pam Conversion tions, being variations of Recipe B, the reactions were run for 1'7 hours at 41 F. Whereas the norgigg g f fifg gffifigg ggt:-- 8:832 mal practice is to charge the soap masterbatch chrom pentflhydraten 3.5% 13-? 45 (emulsifier, KOI-I, dispersing agent and KCl and 1 322225 a e sugar), the styrene and modifier, the butad1ene, mercurons chloride 0.047 5.7 cobaltous mum 058 m then cool and mJect activator and finally catalyst cqg a fous c g hexahydrateufl 3- m each case the practice of making up the activam m a calcium chloride 0.033 1.6 tor in larger volume, 1. e. 40 parts (4 times norgggg ggmggeggggg f fi f 3 8% 33 mal) of w er and charging ahead of butadiene has been followed:

Variations in Oharging- Conv., Variations in Charging- Conv.,

Recipe B Percent Example III Per e t 1. Normal 78 Normal 53 2. Ferrous pyrophosphate 49.4 Potassium ethylene dinitrilo 42.4

activator made up in 4 tetra acetate made up in 4 times normal water dextrose times normal water. Invert digested in 40 parts 01% sugar undigested. Added KOH added both ahead of ahead of hydrocarbons. hydrocarbons. 3. Dextrose digested with py- 53.7 Invert sugar and potassium 36.1

rophosphate in 40 parts ethylene dinitrilo tetra acewater cooled to F. tate dissolved in 40 parts FQSOLIHQO added, aged water and FeSO .7H=0 add- 140 F. for 30 min. Added ed-all added ahead of ahead of hydrocarbons. hydrocarbons. 4. Dextrose digested with py- 27.4 Invert sugar and potassium 45.3

rophosphate in 40 parts ethylene dinitrilo tetra acewater, added to soap masttate dissolved in 40 parts erbatch, cooled to 140 F., water, mixed with soap FQSO4.7H30 added aged masterbatch FeSO4.7H;O 10 min. 140 F. :gdded ahead of hydrocarcos. 5. Dextrose,soap master- 35. 1 Same as above since no digesbatch and pyrophosphate tron. made up in 40 parts water, digested, cooled to 140 F, FeSOflHzO added and the 7 whole aged 30 min. at 0. Same as above but imaged 38. 5 do at140 F.

We claim:

1. The process which comprises causing substances selected from the group consisting of butadiene-1,3 and admixtures thereof with copolymerizable compounds to polymerize at a low temperature with a peroxy initiator in aqueous emulsion in the presence of a water-soluble organic chelate complex of a salt of ethylene dinitrilo tetra acetic acid and iron and an alkali metal.

2. The process which comprises causing substances selected from the group consisting of butadiene-l,3 and admixtures thereof with copolymerizable compounds to polymerize at low temperature with a peroxy initiator in aqueous emulsion in the presence of an activatin sugar and of a water-soluble organic chelate complex of, a salt of ethylene dinitrilo tetra acetic acid and iron and an alkali metal.

3. The process which comprises causing substances selected from the group consisting of conjugated dienes and admixtures thereof with cpolymerizable compounds to polymerize with a peroxy initiator in aqueous emulsion in the presence of a water-soluble organic chelate complex of a compound selected from the group consisting of compounds of the general formula that i t 1'1 i and water-soluble salts-thereof, R being an alkyl carboxyl group.

4. The process which comprises causing sub stances selected from the group consisting of butadiene-1,3 and admixtures thereof with copolymerizable compounds to polymerize with a peroxy initiator in. aqueous emulsion in the presence of a. water-soluble organic chelate complex of a compound selected from the group consisting of compounds of the general formula and water-soluble salts thereof, R, being an alkyl carboxyl group.

5. The process which comprises causing substances selected from the group consisting of conjugated dienes and admixtures thereof with copolymerizable compounds to polymerize at a low temperature with a peroxy initiator in aqueous emulsion in the presence of a water-soluble organic chelate complex of a compound selected from the group consisting of compounds of the general formula H R i r-o-d-r i III L and water-soluble salts thereof, B. being an alkyl carboxyl group.

6. The process which comprises causing substances selected from the group consisting of conjugated dienes and admixtures thereof with copolymerizable compounds to polymerize with a peroxy initiator in aqueous emulsion in the presence of an activating sugar and of a water-soluble organic chelate complex of a compound selected from the group consisting of compounds of the general formula ct-tut Meet 10 and water-soluble salts thereof, B. being an alkyl carboxyl group.

7. The process which comprises causing substances selected from the group consisting of conjugated dienes and admixtures thereof with copolymerizable compounds to polymerize with a peroxy initiator in aqueous emulsion in the presence of a water-soluble organic chelate complex of ethylene dinitrilo tetra acetic acid.

8. The process which comprises causing substances seleoted from the group consisting of conjugated dienes and admixtures thereof with copolymerizable compounds to polymerize with a peroxy initiator in aqueous emulsion in the presence of a water-soluble organic chelate complex of a water-soluble salt of ethylene dinitrilo tetra acetic acid.

9. The process which comprises causing substances selected from the group consisting of butadiene-l,3 and admixtures thereof with copolymerizable compounds to polymerize at a low temperature with a peroxy initiator in aqueous emulsion in the presence of a water-soluble organic chelate complex of ethylene dinitrilo tetra acetic acid.

10. The process which comprises causing substances selected from the group consisting of butadiene-1,3 and admixtures thereof with copolymerizable compounds to polymerize at a low temperature with a peroxy initiator in aqueous emulsion in the presence of a water-soluble organic chelate complex of a water-soluble salt of ethylene dinitrilo tetra acetic acid.

11. The process which comprises causing substances selected from the group consisting of butadiene-LB and admixtures thereof with copolymerizable compounds to polymerize at low temperature with a peroxy initiator in aqueous emulsion in the presence of an activating sugar and of a water-soluble organic chelate complex of ethylene dinitrilo tetra acetic acid.

12. The process which comprises causing substances selected from the group consisting of butadiene1,3 and admixtures thereof with 00- polymerizable compounds to polymerize at low temperature with a peroxy initiator in aqueous emulsion in the presence of an activating sugar and of a water-soluble organic chelate complex of a water-soluble salt of ethylene dinitrilo tetra acetic acid.

13. The process which comprises causing substances selected from the group consisting of conjugated dienes and admixtures thereof with copolymerizable compounds to polymerize with a peroxy initiator in aqueous emulsion in the presence of a water-soluble organic chelate complex of an iron salt of a compound selected from the group consisting of compounds of the general formula l I H l NO-l i i H i and water-soluble salts thereof, R being an alkyl carboxyl group.

14. The process which comprises causing substances selected from the group consisting of butadiene-1,3 and admixtures thereof with copolymerizable compounds to polymerize with a peroxy initiator in aqueous emulsion in the presence of a water-soluble organic chelate complex of an iron salt of a compound selected from the 11 "group consisting of compounds of the general formula R H H R taint i it t t and water-soluble salts thereof, B, being an alkyl carboxyl group.

15. The process which comprises causing substances selected from the group consisting of conjugated dienes and admixtures thereof with copolymerizable compounds to polymerize at a low temperature with a peroxy initiator in aqueous emulsion in the presence of a water-soluble organic chelate complex of an iron salt of a compound selected from the group consisting of compounds of the general formula R H fiat-tat i t 1'1 i and water-soluble salts thereof, R bein an alkyl carboxyl group.

17. The process which comprises causing substances selected from the group consisting of conjugated dienes and admixtures thereof with co-' polymerizable compounds to polymerize with a peroxy initiator in aqeous emulsion in the presence of a water-soluble organic chelate complex of an iron salt of ethylene dinitrilo tetra acetic acid.

18. The process which comprises causing substances selected from the group consisting of conjugated dienes and admixtures thereof with copolymerizable compounds to polymerize with a peroxy initiator in aqueous emulsion in the presence of a watersoluble organic chelate complex of an iron salt of a water-soluble salt of ethylene dinitrilo tetra acetic acid.

19. The process which comprises causing substances selected from the group consisting of butadiene-1,3 and admixtures thereof with copolymerizable compounds to polymerize at a low temperature with a peroxy initiator in aqueous emulsion in the presence of a water-soluble organic chelate complex of an iron salt of ethylene dinitrilo tetra acetic acid.

20. The process which comprises causing substances selected from the group consisting of butadiene-1,3 and admixtures thereof with copolymerizable compounds to polymerize at .a low temperature with a peroxy initiator in aqueous emulsion in the presence of a water-soluble organic chelate complex of an iron salt of a watersoluble salt of ethylene dinitrilo tetra acetic acid.

21. The process which comprises causing substances selected from the group consisting of butadiene-1,3 and admixtures thereof with 00- polymerizable compounds to polymerize at a low temperature with a peroxy initiator in aqueous emulsion in the presence of an activating sugar and of a water-soluble organic chelate complex of an iron salt of ethylene dinitrilo tetra acetic acid.

22. The process which comprises causing substances selected from the group consisting of butadiene-L3 and admixtures thereof with copolymerizable compounds to polymerize at a low temperature with a peroxy initiator in aqueous emulsion in the presence of an activating sugar and of a water-soluble organic chelate complex of an iron salt of a water-soluble salt of ethylene dinitrilo tetra acetic acid.

H. LEVERNE WILLIAMS. J. MAXWELL MITCHELL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Uraneck Dec. 18, 1951 Number 

1. THE PROCESS WHICH COMPRISES CAUSING SUBSTANCES SELECTED FROM THE GROUP CONSISTING OF BUTADIENE-1,3 AND ADMIXTURES THEREOF WITH COPOLYMERIZABLE COMPOUNDS TO POLYMERIZE AT A LOW TEMPERATURE WITH A PEROXY INITIATOR IN AQUEOUS EMULSION IN THE PRESENCE OF A WATER-SOLUBLE ORGANIC CHELATE COMPLEX OF A SALT OF ETHYLENE DINITRILO TETRA ACETIC ACID AND IRON AND AN ALKALI METAL. 